Java Reference
In-Depth Information
The final step of the algorithm is to display the value of
y
. This can be achieved by the
following two lines.
System. out . print (
"The temperature in Fahrenheit is: "
);
System. out . println (y) ;
The first line prints the string that is specified in the double quotes. Note that all string
literals in Java need to be surrounded by double quotes. The second line prints the value of
y
.Notethatthe
print
method can take any input: for example, integer, double, character,
and even an object. The second line of the code uses the
println
method instead of the
print
method because we want to print a new line at the end.
With small modifications, our degree Fahrenheit to degree Celsius program will look as
follows.
1
package
helloworld ;
2
import
java . util .
;
∗
3
4
public class
Main
{
5
public static void
main(String args [])
{
6
int
x;
7
double
y,c;
8
System . out . p r i n t (
"Enter temperature is Celsius: "
);
9
Scanner keyboard =
new
Scanner(System. in) ;
10
x=keyboard . nextInt () ;
11
c = 9/5;
12
y = 32+c
∗
x;
13
System . out . p r i n t (
"The temperature in Fahrenheit is: "
);
14
System . out . p r i n t l n ( y ) ;
15
}
16
}
Let us first examine the program line by line. Line 1 defines the package. From now on,
for simplicity, we will create the programs in the default package and omit the package line.
Note that defining the package is a statement and, as such, is followed by a semicolon. If
we delete the semicolon, NetBeans will underline the whole line in red. If we hover over the
red line with the mouse, it will tell us that we have forgotten the semicolon. Line 2 tells
Java that we want to use the
java.util
library. This is where most of the utility classes
are stored. For example, we need this library in order to read input from the keyboard.
Since this is such an important library, we will include it in almost every program. Note
that some of our example programs will skip the
import
section. In order to see how to
reproduce the
include
lines, delete the second line of the code. The
Scanner
class will now
be underlined in red indicating an error. Right-click on the code that is underlined in red
and select
Fix Imports
. You will be given a chance to add the import that you need. In
our case, we can select
java.util.Scanner
.Notethat
import java.util.*
imports all
classes from the library
java.util
. Conversely, the statement
import java.util.Scanner
imports only the
Scanner
class library.
